Calibration of vehicle and smartphone coordinate systems includes receiving acceleration data from an accelerometer of the smartphone. The smartphone identifies a Y-axis, a z-axis, and an x-axis of the coordinate system of the vehicle relative to a coordinate system of the smartphone from the raw acceleration data. The smartphone generates processed acceleration data by transforming the raw acceleration data into the coordinate system of the smartphone. The processed acceleration data is used to detect driving conditions of the vehicle.
|
1. A computer-implemented method comprising:
receiving raw acceleration data generated by an accelerometer of a smartphone, the smartphone being in a vehicle;
identifying a gravity vector from the raw acceleration data;
using the gravity vector, decomposing raw linear acceleration data from the acceleration data into a vertical vector and a horizontal vector;
identifying a Y-axis, a z-axis, and an x-axis of a coordinate system of the vehicle relative to a coordinate system of the smartphone from the raw acceleration data by identifying a z-axis vector of the vehicle from the gravity vector, identifying an x-axis vector of the vehicle by analyzing a plurality of horizontal vectors detected within a time interval, and identifying a Y-axis vector of the vehicle by taking a cross product of the x-axis vector and the z-axis vector of the vehicle;
generating processed acceleration data by transforming the raw acceleration data into the coordinate system of the vehicle; and
detecting a driving condition of the vehicle using the processed acceleration data.
3. A computer-implemented method comprising:
receiving raw acceleration data generated by an accelerometer of a smartphone, the smartphone being in a vehicle;
determining a gravity vector from the raw acceleration data;
using the gravity vector, decomposing a linear acceleration vector into a vertical vector and a horizontal vector;
identifying an x-axis of a coordinate system of the vehicle by transforming a plurality of horizontal vectors to polar representation and identifying a direction of the x-axis of the coordinate system of the vehicle from angles of the polar representation of the plurality of horizontal vectors;
performing a cross-product of a z-axis of the coordinate system of the vehicle with the x-axis of the coordinate system of the vehicle to identify the Y-axis of the coordinate system of the vehicle, the z-axis being identified from the gravity vector; and
detecting an acceleration force vector on the vehicle by transforming the linear acceleration vector from a coordinate system of the smartphone to the coordinate system of the vehicle, the linear acceleration data being obtained from the raw acceleration data using the gravity vector.
5. A smartphone comprising:
an accelerometer that generates raw acceleration data;
a processor; and
a memory comprising instructions executed by the processor to cause the smartphone to perform the steps of:
receiving raw acceleration data generated by an accelerometer of a smartphone, the smartphone being in a vehicle;
identifying a gravity vector from the raw acceleration data;
using the gravity vector, decomposing raw linear acceleration data from the acceleration data into a vertical vector and a horizontal vector;
identifying a Y-axis, a z-axis, and an x-axis of a coordinate system of the vehicle relative to a coordinate system of the smartphone from the raw acceleration data by identifying a z-axis vector of the vehicle from the gravity vector, identifying an x-axis vector of the vehicle by analyzing a plurality of horizontal vectors detected within a time interval, and identifying a Y-axis vector of the vehicle from a cross product of the x-axis vector and the z-axis vector of the vehicle;
generating processed acceleration data by transforming the raw acceleration data into the coordinate system of the vehicle; and
detecting a driving condition of the vehicle using the processed acceleration data.
4. The method of
splitting a reference polar coordinate system into a plurality of units;
projecting the angles of the polar representation of the horizontal vectors into corresponding units in the plurality of units; and
detecting the direction of the x-axis of the coordinate system of the vehicle from statistics of the horizontal vectors in the plurality of units.
6. The smartphone of
|
1. Field of the Invention
The present invention relates generally to smartphones, and more particularly but not exclusively to methods and apparatus for calibrating vehicle and smartphone coordinate systems.
2. Description of the Background Art
Smartphones are mobile telephones that include computing resources for data processing and data communications. Some smartphones further include various sensors, such as a 3-axis accelerometer and a 3-axis magnetic field sensor, and have an integrated global positioning system (GPS). Examples of currently-available smartphones include the APPLE IPHONE and ANDROID smartphones.
Smartphone sensors may be employed in a variety of vehicle-related applications, such as driving habits detection, car accident detection, and the like. Because the orientation of a smartphone relative to a vehicle varies depending on how the user (driver or passenger) of the vehicle carries the smartphone, these vehicle-related applications require calibration of the coordinate system of the smartphone to that of the vehicle. More particularly, information from smartphone sensors is relative to the smartphone, not the vehicle. Therefore, to understand the movement of the vehicle, information from smartphone sensors need to be translated in terms of the vehicle's coordinate system.
One calibration method involves mounting the smartphone at a fixed position that is aligned with the vehicle's coordinate system. Although this calibration method is relatively simple, it is inconvenient to the user as the smartphone needs to be manually mounted and dismounted. This method also prevents or makes it difficult to use the smartphone for other purposes.
Another method of calibrating the coordinate systems of the smartphone and the vehicle requires the use of a GPS and a 3-axis magnetic field sensor. In this method, the smartphone's coordinate system is transferred to the world's coordinate system using sensor information from the smartphone's accelerometer and the 3-axis magnetic field sensor. The world's coordinate system is then transferred to the vehicle's coordinate system using GPS information. Although this method works independent of the orientation of the smartphone, not all smartphones are equipped with a GPS. Furthermore, GPS increases power consumption of the smartphone, is not available in certain locations, and may be inaccurate depending on the smartphone.
In one embodiment, calibration of vehicle and smartphone coordinate systems includes receiving acceleration data from an accelerometer of the smartphone. The smartphone identifies a Y-axis, a Z-axis, and an X-axis of the coordinate system of the vehicle relative to the coordinate system of the smartphone from the raw acceleration data. The smartphone generates processed acceleration data by transforming the raw acceleration data into the coordinate system of the smartphone. The processed acceleration data may be used to detect driving conditions of the vehicle.
These and other features of the present invention will be readily apparent to persons of ordinary skill in the art upon reading the entirety of this disclosure, which includes the accompanying drawings and claims.
The use of the same reference label in different drawings indicates the same or like components.
In the present disclosure, numerous specific details are provided, such as examples of apparatus, components, and methods, to provide a thorough understanding of embodiments of the invention. Persons of ordinary skill in the art will recognize, however, that the invention can be practiced without one or more of the specific details. In other instances, well-known details are not shown or described to avoid obscuring aspects of the invention.
Referring now to
The smartphone 100 further includes an accelerometer 107, which in one embodiment comprises a 3-axis accelerometer for measuring acceleration forces. The smartphone 100 may include additional sensors, but they are not necessary to perform the smartphone-vehicle coordinate system calibration described herein. For example, in one embodiment, the smartphone 100 does not have a GPS, making the calibration techniques described herein especially suitable with the smartphone 100.
The smartphone 100 is a particular machine as programmed with computer-readable program code. The smartphone 100 includes computer-readable program code loaded non-transitory in the main memory 108 for execution by the processor 101. In the example of
The calibration module 113 may comprise computer-readable program code for calibrating the coordinate systems of the smartphone 100 and a vehicle. The calibration module 113 may also be implemented as firmware or programmed logic hardware.
In one embodiment, the calibration module 113 receives raw acceleration data that are generated by the accelerometer 107, determines a gravity vector that represents the Z-axis vector of the vehicle in the coordinate system of the smartphone from the raw acceleration data, uses the gravity vector to decompose linear acceleration data into vertical vectors and horizontal vectors, analyzes the horizontal vectors to identify the X-axis vector of the vehicle in the coordinate system of the smartphone, identifies the Y-axis vector of the vehicle from the X-axis and Z-axis vectors of the vehicle, and generates processed acceleration data by transforming the raw acceleration data from the smartphone's coordinate system into the vehicle's coordinate system.
An application 114 may comprise an application program, referred to as an “app” in the art of smartphones, for receiving processed acceleration data from the calibration module 113. Processed acceleration data is acceleration data along the vehicle's coordinate system, and is thus useful in determining acceleration force vectors, i.e., acceleration force magnitude and direction, relative to the vehicle's orientation. The application 114 may use the processed acceleration data to detect driving conditions, such as collisions, road conditions, drunk driving, driving habits of the driver, and other conditions that may be detected based on acceleration forces on the vehicle.
In the example of
The calibration module 113 analyzes all horizontal vectors H detected within a time interval to identify the X-axis, the Y-axis, and the Z-axis of the vehicle's coordinate system in the coordinate system of the smartphone 100 (step 203). In one embodiment, the calibration module 113 identifies the three axes of the coordinate system of the vehicle by analyzing the horizontal vectors H to identify the X-axis vector of the vehicle in the coordinate system of the smartphone 100 (step 204) and by identifying the Y-axis vector of the vehicle in the coordinate system of the smartphone 100 (step 205). The Z-axis vector of the vehicle in the coordinate system of the smartphone may be obtained from the gravity vector G, and the Y-axis vector of the vehicle in the coordinate system of the smartphone may be obtained from a cross-product of the Z-axis and X-axis vectors of the vehicle.
In one embodiment, the calibration module 113 identifies the X-axis vector of the vehicle in the coordinate system of the smartphone 100 by detecting the straight-line accelerated and decelerated motions of the vehicle within a time interval. More particularly, within a period of time, the straight-line accelerations and decelerations of the vehicle will be much more frequent than turning and lane change motions. The straight-line accelerations and decelerations are also relatively balanced. Ideally, accelerated and decelerated motions in a straight line generate acceleration vectors along the positive X-axis and negative X-axis directions, respectively. In practice, considering various noises, the statistic rule is that the number of horizontal vectors H near or on the X-axis can take a large proportion in all of the horizontal vectors H, and is relatively balanced along the positive and negative directions of the X-axis within a period of time. In one embodiment, the calibration module 113 identifies the X-axis vector of the vehicle by detecting for horizontal vectors in accordance with the just-mentioned statistic rule.
After identifying the X-axis vector of the vehicle in the coordinate system of the smartphone 100, the calibration module 113 may identify the Y-axis vector of the vehicle in the coordinate system of the smartphone 100 from the cross-product of the Z-axis and X-axis vectors of the vehicle in the coordinate system of the smartphone 100. The X-axis vector, Y-axis vector, and Z-axis vector of the vehicle represent the positive X-axis, positive Y-axis, and positive Z-axis of the vehicle's coordinate system, respectively. Therefore, at this point of the method 200, the three axes of the coordinate system of the vehicle in the coordinate system of the smartphone 100 have been identified. This allows the calibration module 113 to transform raw acceleration data (which is relative to the coordinate system of the smartphone 100) into the coordinate system of the vehicle (step 206). That is, given raw acceleration data from the accelerometer 107, the calibration module 113 is now able to transform the raw acceleration data into processed acceleration data, which indicates acceleration force vectors along the coordinate system of the vehicle. The calibration module 113 may provide the processed acceleration data to the application 114, which may use the processed acceleration data to detect the movement of the vehicle for various purposes, including detection of driving conditions (step 207).
Referring first to the method 250 of
G=(GX,GY,GZ) (EQ. 1)
where GX, GY and GZ are averages of all the measurements on those respective axes for the time interval. The linear acceleration vector L caused by an external force other than gravity may be expressed as,
L=(AX−GX,AY−GY,AZ−GZ) (EQ. 2)
After calculating the gravity vector G, the calibration module 113 decomposes a linear acceleration vector L into a vertical vector V and a horizontal vector H (step 252). The vertical vector V is the projection of the linear acceleration vector L upon the vertical axis represented by the gravity vector G. The vertical vector V may be calculated using one of several methods, e.g., projection angle or vector dot products such as in EQ. 3.
A 3-dimensional (3D) vector is a sum of vertical and horizontal components, so
H=L−V (EQ. 4)
In theory, a horizontal vector H can point to any direction on the horizontal plane that is perpendicular to a vertical vector V.
The calibration module 113 analyzes a set {H1, H2, H3 . . . , HN} of horizontal vectors to identify the three axes of the vehicle's coordinate system in the coordinate system of the smartphone 100 (step 253). In one embodiment, this processing step is performed by the calibration module 113 using the method 260 of
The calibration module 113 analyzes the set {{circle around (-)}1, {circle around (-)}2, . . . , {circle around (-)}N} of polar angles to identify the direction of the X-axis of the coordinate system of the vehicle in the reference polar coordinate system (step 262). In one embodiment, this processing step is performed by the calibration module 113 using the method 270 of
Continuing the method 270 of
Returning to
Returning to
L′=R×L (EQ. 5)
where each row of the rotation matrix R represents the projections of the vehicle's axes onto the coordinate system of the smartphone 100.
In the beginning of the method 290, a time interval for performing the calibration (e.g., every few seconds) is chosen and the initial value of the vehicle's coordinate system is set to NULL, indicating no calibration has occurred. In one embodiment, the vehicle's coordinate system is represented by a rotation matrix R, which is set to NULL, i.e., with no values, during initialization. Thereafter, the calibration module 113 receives raw acceleration data generated by the accelerometer 107 (step 291). The calibration module 113 analyzes the raw acceleration data within a given time interval to detect the vehicle's coordinate system relative to the smartphone's coordinate system (step 292). This process step involves calibration of the smartphone's coordinate system to the vehicle's coordinate system using the raw acceleration data as previously described to generate a candidate rotation matrix R′. When the vehicle's coordinate system has remained NULL, the calibration module 113 loops back to receive and analyze raw acceleration data (path from step 293 to step 294 to step 291).
When the vehicle's coordinate system has changed, i.e., the candidate rotation matrix R′ is different from the current rotation matrix R, the calibration module 113 updates the current rotation matrix R with the candidate rotation matrix R′ (step 293 to step 295). That is, the candidate rotation matrix R′ becomes the current rotation matrix (R=R′). The calibration module 113 keeps the current rotation matrix R when it has not changed and the current rotation matrix R is not NULL (path from step 293 to step 294 to step 296). The calibration module 113 then transforms the raw acceleration data into the vehicle coordinate system using the current rotation matrix R (step 296). The processed acceleration data, i.e., transformed to the vehicles coordinate system, may then be employed to detect driving conditions.
Methods and apparatus for calibrating vehicle and smartphone coordinate systems using acceleration data have been disclosed. While specific embodiments of the present invention have been provided, it is to be understood that these embodiments are for illustration purposes and not limiting. Many additional embodiments will be apparent to persons of ordinary skill in the art reading this disclosure.
Chen, Gang, Zhao, Xiaoming, Dong, Kan
Patent | Priority | Assignee | Title |
10067157, | May 07 2015 | CAMBRIDGE MOBILE TELEMATICS INC | Methods and systems for sensor-based vehicle acceleration determination |
10078099, | Jun 24 2014 | CAMBRIDGE MOBILE TELEMATICS INC | Methods and systems for aligning a mobile device to a vehicle |
10168156, | Mar 23 2017 | International Business Machines Corporation | Orient a mobile device coordinate system to a vehicular coordinate system |
10462608, | Jul 31 2017 | AGERO, INC | Estimating orientation of a mobile device with respect to a vehicle using global displacement information and local motion information |
10568148, | Jan 24 2017 | Toyota Jidosha Kabushiki Kaisha | Systems and methods for communicating notices within a vehicle using a mobile device |
10812943, | May 24 2019 | BEIJING XIAOMI MOBILE SOFTWARE CO., LTD. | Method and device for sensing terminal action |
10845381, | Jun 24 2014 | CAMBRIDGE MOBILE TELEMATICS INC | Methods and systems for pattern-based identification of a driver of a vehicle |
10850766, | Feb 01 2019 | Ford Global Technologies, LLC | Portable device data calibration |
11237184, | Jun 24 2014 | CAMBRIDGE MOBILE TELEMATICS INC | Methods and systems for pattern-based identification of a driver of a vehicle |
11361379, | May 12 2014 | Esurance Insurance Services, Inc. | Transmitting driving data to an insurance platform |
9897449, | Dec 07 2015 | YAHOO JAPAN CORPORATION | Determination device, determination method, and non-transitory computer readable storage medium |
Patent | Priority | Assignee | Title |
6464144, | May 18 2000 | Symbol Technologies, LLC | Hand held terminal with an odor sensor |
20060010699, | |||
20060245300, | |||
20080305735, | |||
20100048167, | |||
20130046505, | |||
20140009256, | |||
20140149145, | |||
20140330530, |
Executed on | Assignor | Assignee | Conveyance | Frame | Reel | Doc |
Mar 05 2013 | TREND MICRO INCORPORATED | (assignment on the face of the patent) | / | |||
Mar 05 2013 | DONG, KAN | TREND MICRO INCORPORATED | ASSIGNMENT OF ASSIGNORS INTEREST SEE DOCUMENT FOR DETAILS | 030195 | /0809 | |
Mar 05 2013 | ZHAO, XIAOMING | TREND MICRO INCORPORATED | ASSIGNMENT OF ASSIGNORS INTEREST SEE DOCUMENT FOR DETAILS | 030195 | /0809 | |
Mar 05 2013 | CHEN, GANG | TREND MICRO INCORPORATED | ASSIGNMENT OF ASSIGNORS INTEREST SEE DOCUMENT FOR DETAILS | 030195 | /0809 |
Date | Maintenance Fee Events |
Jul 24 2019 | M1551: Payment of Maintenance Fee, 4th Year, Large Entity. |
Aug 02 2023 | M1552: Payment of Maintenance Fee, 8th Year, Large Entity. |
Date | Maintenance Schedule |
Feb 02 2019 | 4 years fee payment window open |
Aug 02 2019 | 6 months grace period start (w surcharge) |
Feb 02 2020 | patent expiry (for year 4) |
Feb 02 2022 | 2 years to revive unintentionally abandoned end. (for year 4) |
Feb 02 2023 | 8 years fee payment window open |
Aug 02 2023 | 6 months grace period start (w surcharge) |
Feb 02 2024 | patent expiry (for year 8) |
Feb 02 2026 | 2 years to revive unintentionally abandoned end. (for year 8) |
Feb 02 2027 | 12 years fee payment window open |
Aug 02 2027 | 6 months grace period start (w surcharge) |
Feb 02 2028 | patent expiry (for year 12) |
Feb 02 2030 | 2 years to revive unintentionally abandoned end. (for year 12) |